Providing estimated accuracy of mobile station synchronization to the network

ABSTRACT

A mobile station (MS), a base station subsystem (BSS), and various methods are described herein that enable a positioning node (e.g., Serving Mobile Location Center (SMLC)) to improve the accuracy of estimating a position of the mobile station.

CLAIM OF PRIORITY

This application claims the benefit of priority to U.S. ProvisionalApplication Ser. No. 62/415,990, filed on Nov. 1, 2016, the entirecontents of which are hereby incorporated herein by reference for allpurposes.

RELATED PATENT APPLICATIONS

This application is related to the co-filed U.S. patent application Ser.No. 15/799,037 entitled “Providing Estimated Accuracy of Mobile StationSynchronization and Mobile Station Transmission Offset to the Network”.This application is also related to the co-filed U.S. patent applicationSer. No. 15/798,928 entitled “Providing Estimated Accuracy of MobileStation Synchronization to the Network”.

TECHNICAL FIELD

The present disclosure relates generally to the wirelesstelecommunications field and, more particularly, to a mobile station(MS), a base station subsystem (BSS), and various methods that enable apositioning node (e.g., Serving Mobile Location Center (SMLC)) toimprove the accuracy of estimating a position of the mobile station.

BACKGROUND

The following abbreviations are herewith defined, at least some of whichare referred to within the following description of the presentdisclosure.

-   3GPP 3rd-Generation Partnership Project-   APDU Application Protocol Data Unit-   ASIC Application Specific Integrated Circuit-   BSS Base Station Subsystem-   BBSLAP Base Station Subsystem Location Services Assistance Protocol-   BSSMAP Base Station Subsystem Mobile Application Part-   BSSMAP-LE BSSMAP-Location Services Extension-   BTS Base Transceiver Station-   CN Core Network-   DSP Digital Signal Processor-   EC Extended Coverage-   EC-GSM Extended Coverage Global System for Mobile Communications-   EDGE Enhanced Data rates for GSM Evolution-   EGPRS Enhanced General Packet Radio Service-   eNB Evolved Node B-   GSM Global System for Mobile Communications-   GERAN GSM/EDGE Radio Access Network-   GPRS General Packet Radio Service-   IE Information Element-   IoT Internet of Things-   LAC Location Area Code-   LTE Long-Term Evolution-   MCC Mobile Country Code-   MME Mobility Management Entity-   MNC Mobile Network Code-   MS Mobile Station-   MTA Multilateration Timing Advance-   MTC Machine Type Communications-   NB-IoT Narrow Band Internet of Things-   PDN Packet Data Network-   PDU Protocol Data Unit-   PLMN Public Land Mobile Network-   RAN Radio Access Network-   RLC Radio Link Control-   SGSN Serving GPRS Support Node-   SMLC Serving Mobile Location Center-   TA Timing Advance-   TBF Temporary Block Flow-   TLLI Temporary Logical Link Identifier-   TS Technical Specification-   TSG Technical Specification Group-   UE User Equipment-   UL Uplink-   WCDMA Wideband Code Division Multiple Access-   WiMAX Worldwide Interoperability for Microwave Access

At the 3rd-Generation Partnership Project (3GPP) Technical SpecificationGroup (TSG) Radio Access Network (RAN) Meeting #72, a Work Item on“Positioning Enhancements for GERAN” was approved (see RP-161260; Busan,Korea; 13-16 Jun. 2016—the contents of which are hereby incorporatedherein by reference), wherein one candidate method for realizingimproved accuracy when determining the position of a mobile station (MS)is timing advance (TA) multilateration (see RP-161034; Busan, Korea;13-16 Jun. 2016—the contents of which are hereby incorporated herein byreference), which relies on establishing the MS position based on TAvalues in multiple cells.

At the 3GPP TSG-RAN1 Meeting #86, a proposal based on a similar approachwas made also to support positioning of Narrow Band Internet of Things(NB-IoT) mobiles (see R1-167426; Gothenburg, Sweden; 22-26 Aug. 2016—thecontents of which are hereby incorporated herein by reference).

TA is a measure of the propagation delay between a base transceiverstation (BTS) and the MS, and since the speed by which radio wavestravel is known, the distance between the BTS and the MS can be derived.Further, if the TA applicable to the MS is measured within multiple BTSsand the positions of these BTSs are known, the position of the MS can bederived using the measured TA values. The measurement of the TA requiresthat the MS synchronize to each neighbor BTS and transmit a signaltime-aligned with the estimated timing of the downlink channel receivedfrom each BTS. The BTS measures the time difference between its own timereference for the downlink channel, and the timing of the receivedsignal (transmitted by the MS). This time difference is equal to twotimes the propagation delay between the BTS and the MS (one propagationdelay of the BTS's synchronization signal sent on the downlink channelto the MS, plus one equal propagation delay of the signal transmitted bythe MS back to the BTS).

Once the set of TA values are established using a set of one or moreBTSs during a given positioning procedure, the position of the MS can bederived through so called multilateration wherein the position of the MSis determined by the intersection of a set of hyperbolic curvesassociated with each BTS (see FIG. 1). The calculation of the positionof the MS is typically carried out by a serving positioning node (i.e.,serving Serving Mobile Location Center (SMLC)), which implies that allof the derived TA and associated BTS position information needs to besent to the positioning node (i.e., the serving SMLC) that initiated thepositioning procedure.

Referring to FIG. 1 (PRIOR ART) there is shown a diagram of an exemplarywireless communication network 100 used to help explain a problemassociated with the traditional multilateration process in determining aposition of a mobile station 102 (MS 102). The exemplary wirelesscommunication network 100 has several nodes which are shown and definedherein as follows:

-   -   Foreign BTS 104 ₃: A BTS 104 ₃ (shown as foreign BTS3 104 ₃)        associated with a BSS 106 ₃ (shown as non-serving BSS3 106 ₃)        that uses a positioning node 108 ₂ (shown as non-serving SMLC2        108 ₂) that is different from a positioning node (shown as        serving SMLC1 108 ₁) which is used by the BSS 106 ₁ (shown as        serving BSS1 106 ₁) that manages the cell serving the MS 102        when the positioning (multilateration) procedure is initiated.        The derived TA information (TA3 114 ₃) and identity of the        corresponding cell are relayed by the BSS 106 ₃ (shown as        non-serving BSS3 106 ₃), the SGSN 110 (core network), and the        BSS 106 ₁ (shown as serving BSS1 106 ₁) to the serving        positioning node (shown as serving SMLC1 108 ₁) (i.e., in this        case the non-serving BSS3 106 ₃ has no context for the MS 102).        The BSS 106 ₃ (shown as non-serving BSS3 106 ₃) can be        associated with one or more BTSs 104 ₃ (only one shown) and a        BSC 112 ₃ (shown as non-serving BSC3 112 ₃).    -   Local BTS 104 ₂: A BTS 104 ₂ (shown as local BTS2 104 ₂)        associated with a BSS 106 ₂ (shown as non-serving BSS2 106 ₂)        that uses the same positioning node 108 ₁ (shown as serving        SMLC1 108 ₁) as the BSS 106 ₁ (shown as serving BSS1 106 ₁) that        manages the cell serving the MS 102 when the positioning        (multilateration) procedure is initiated. The derived TA        information (TA2 114 ₂) and identity of the corresponding cell        are relayed by the BSS 106 ₂ (shown as non-serving BSS2 106 ₂)        and the BSS 106 ₁ (shown as serving BSS1 106 ₁) to the serving        positioning node (shown as serving SMLC1 108 ₁) (i.e., in this        case the non-serving BSS2 106 ₂ has no context for the MS 102)        (i.e., inter-BSS communications allows the non-serving BSS2 106        ₂ to relay the derived TA information (TA2 114 ₂) and the        identity of the corresponding cell to the serving BSS1 106 ₁).        The BSS 106 ₂ (shown as non-serving BSS2 106 ₂) can be        associated with one or more BTSs 104 ₂ (only one shown) and a        BSC 112 ₂ (shown as non-serving BSC2 112 ₂).    -   Serving BTS 104 ₁: A BTS 104 ₁ (shown as serving BTS1 104 ₁)        associated with a BSS 106 ₁ (shown as serving BSS1 106 ₁) that        manages the cell serving the MS 102 when the positioning        (multilateration) procedure is initiated. The derived TA        information (TA1 114 ₁) and identity of the corresponding cell        are sent directly by the BSS 106 ₁ (shown as serving BSS1 106 ₁)        to the serving positioning node 108 ₁ (shown as serving SMLC1        108 ₁) (i.e., in this case the serving BSS1 106 ₁ has a context        for the MS 102). The BSS 106 ₁ (shown as serving BSS1 106 ₁) can        be associated with one or more BTSs 104 ₁ (only one shown) and a        BSC 112 ₁ (shown as serving BSC1 112 ₁).    -   Serving SMLC 108 ₁: The SMLC 108 ₁ (shown as serving SMLC1 108        ₁) that commands the MS 102 to perform the positioning        (multilateration) procedure (i.e., the SMLC 108 ₁ sends a Radio        Resource Location services Protocol (RRLP) Multilateration        Request to the MS 102).    -   Serving BSS 106 ₁: The BSS 106 ₁ (shown as serving BSS1 106 ₁)        associated with the serving BTS 104 ₁ (shown as serving BTS1 104        ₁) (i.e., the BSS 106 ₁ that has context information for the        Temporary Logical Link Identity (TLLI) corresponding to the MS        102 for which the positioning (multilateration) procedure has        been triggered).    -   Non-serving BSS 106 ₂ and 106 ₃: A BSS 106 ₃ (shown as        non-serving BSS3 106 ₃) associated with a foreign BTS 104 ₃        (shown as foreign BTS3 104 ₃) and a BSS 106 ₂ (shown as        non-serving BSS2 106 ₂) associated with a local BTS 104 ₂ (shown        as local BTS2 104 ₂) (i.e., the BSSs 106 ₂ and 106 ₃ do not have        context information for the TLLI corresponding to the MS 102 for        which the positioning (multilateration) procedure has been        triggered).

Note 1: FIG. 1 is an illustration of an exemplary multilaterationprocess involving three BTSs 104 ₁, 104 ₂, and 104 ₃ associated withthree timing advance (TA) values 114 ₁, 114 ₂, 114 ₃ for a particular MS102. The multilateration can involve more than three BTSs 104 ₁, 104 ₂,and 104 ₃ and more than three TA values 114 ₁, 114 ₂, 114 ₃.

Note 2: FIG. 1 is an illustration of an exemplary wireless communicationnetwork 100 showing the basic nodes which are needed to explain thepositioning (multilateration) process. It should be appreciated that theexemplary wireless communication network 100 includes additional nodeswhich are well known in the art.

It is advantageous for the serving SMLC 108 ₁ to estimate the accuracyof the estimated position of the MS 102. The accuracy of the estimatedposition of the MS 102 depends on the number of cell specific TAestimates 114 ₁, 114 ₂, 114 ₃ (for example) it has been provided with,the accuracy of the individual (cell specific) TA estimates 114 ₁, 114₂, 114 ₃ (for example) as well as the MS-BTS geometry, i.e., the trueposition of the MS 102 relative to the involved BTSs 104 ₁, 104 ₂, 104 ₃(for example). The accuracy of the TA estimation in turn depends on theaccuracy by which the MS 102 is able to synchronize to the wirelesscommunication network 100, and the accuracy by which each BTS 104 ₁, 104₂, 104 ₃ (for example) is able to measure the timing of signals receivedfrom the MS 102. The accuracy by which the MS 102 is able to synchronizeto the wireless communication network 100 is currently specified as aworst-case tolerance. For example, a Global System for Mobile telephony(GSM) MS 102 is required to synchronize with an accuracy of ±0.5 symbolperiod (a symbol period being 48/13 μs), see 3GPP TechnicalSpecification (TS) 45.010 V13.3.0 (2016-09)—the contents of thisdisclosure are incorporated herein by reference.

One problem with the existing solution is that the serving SMLC 108 ₁does not have any information about the TA estimation accuracy of theBTS 104 ₁, 104 ₂, 104 ₃ or about the actual MS synchronization accuracy(MS assessment of the BTS timing). If the serving SMLC 108 ₁ assumesthat the accuracy by which the MS 102 is able to synchronize to thewireless communication network 100 is according to the specified worstcase tolerance, the estimated accuracy of the estimated position of theMS 102 may be overly pessimistic. Therefore, services requiring a higherpositioning accuracy may not be provided with a positioning estimate(i.e., it may be concluded that the target positioning accuracy cannotbe realized) even though the actual positioning accuracy may in fact bebetter than estimated and therefore sufficient. Alternatively, theserving SMLC 108 ₁ may involve more BTSs 104 ₁, 104 ₂, 104 ₃ than arenecessary in the positioning process in order to guarantee sufficientaccuracy in the estimated position of the MS 102. These problems andother problems are addressed by the present disclosure.

SUMMARY

A mobile station, a base station subsystem (BSS) and various methods foraddressing the aforementioned problems are described in the independentclaims. Advantageous embodiments of the mobile station, the BSS and thevarious methods are further described in the dependent claims.

In one aspect, the present disclosure provides a mobile stationconfigured to interact with a BSS, wherein the BSS includes a BTS. Themobile station comprises a processor and a memory that storesprocessor-executable instructions, wherein the processor interfaces withthe memory to execute the processor-executable instructions, whereby themobile station is operable to perform a receive operation, an estimateoperation, and a transmit operation. In the receive operation, themobile station receives, from the BSS, a multilateration request. In theestimate operation, the mobile station estimates a synchronizationaccuracy with the BTS in response to the receipt of the multilaterationrequest. In the transmit operation, the mobile station transmits, to theBSS, a RLC data block that includes at least (i) a TLLI of the mobilestation, and (ii) the estimated synchronization accuracy (note: the BSSsubsequently relays this information to the SMLC). An advantage of themobile station performing these operations is that it enables a SMLC tomake a better estimate of the accuracy of the estimated position of themobile station. In addition, for the case where the mobile station doesnot perform these operations, the BSS can provide the SMLC with themobile station's transmission timing accuracy capability informationreceived from the SGSN, thus allowing the SMLC to make an a prioriassessment as to how many BTSs may be needed to reach the desiredposition accuracy and thus provide the mobile station with more accurateassistance information.

In another aspect, the present disclosure provides a method in a mobilestation that is configured to interact with a BSS, wherein the BSSincludes a BTS. The method comprises a receiving step, an estimatingstep, and a transmitting step In the receiving step, the mobile stationreceives, from the BSS, a multilateration request. In the estimatingstep, the mobile station estimates a synchronization accuracy with theBTS in response to receiving the multilateration request. In thetransmitting step, the mobile station transmits, to the BSS, a RLC datablock that includes at least (i) a TLLI of the mobile station, and (ii)the estimated synchronization accuracy (note: the BSS subsequentlyrelays this information to the SMLC). An advantage of the mobile stationperforming these steps is that it enables a SMLC to make a betterestimate of the accuracy of the estimated position of the mobilestation. In addition, for the case where the mobile station does notperform these steps, the BSS can provide the SMLC with the mobilestation's transmission timing accuracy capability information receivedfrom the SGSN, thus allowing the SMLC to make an a priori assessment asto how many BTSs may be needed to reach the desired position accuracyand thus provide the mobile station with more accurate assistanceinformation.

In yet another aspect, the present disclosure provides a BSS whichincludes a BTS and is configured to interact with a mobile station. TheBSS further comprises a processor and a memory that storesprocessor-executable instructions, wherein the processor interfaces withthe memory to execute the processor-executable instructions, whereby theBSS is operable to perform a transmit operation and a receive operation.In the transmit operation, the BSS transmits, to the mobile station, amultilateration request. In the receive operation, the BSS receives,from the mobile station, a RLC data block that includes at least (i) aTLLI of the mobile station, and (ii) an estimated mobile stationsynchronization accuracy, wherein the estimated mobile stationsynchronization accuracy indicates an estimate by the mobile station ofan accuracy by which the mobile station is synchronized to the BTS(note: the BSS subsequently relays this information to the SMLC). Anadvantage of the BSS performing these operations is that it enables aSMLC to make a better estimate of the accuracy of the estimated positionof the mobile station. In addition, for the case where the BSS does notperform these operations, the BSS can provide the SMLC with the mobilestation's transmission timing accuracy capability information receivedfrom the SGSN, thus allowing the SMLC to make an a priori assessment asto how many BTSs may be needed to reach the desired position accuracyand thus provide the mobile station with more accurate assistanceinformation.

In still yet another aspect, the present disclosure provides a method ina BSS which includes a BTS and is configured to interact with a mobilestation. The method comprises a transmitting step and a receiving step.In the transmitting step, the BSS transmits, to the mobile station, amultilateration request. In the receiving step, the BSS receives, fromthe mobile station, a RLC data block that includes at least (i) a TLLIof the mobile station, and (ii) an estimated mobile stationsynchronization accuracy, wherein the estimated mobile stationsynchronization accuracy indicates an estimate by the mobile station ofan accuracy by which the mobile station is synchronized to the BTS(note: the BSS subsequently relays this information to the SMLC). Anadvantage of the BSS performing these steps is that it enables a SMLC tomake a better estimate of the accuracy of the estimated position of themobile station. In addition, for the case where the BSS does not performthese steps, the BSS can provide the SMLC with the mobile station'stransmission timing accuracy capability information received from theSGSN, thus allowing the SMLC to make an a priori assessment as to howmany BTSs may be needed to reach the desired position accuracy and thusprovide the mobile station with more accurate assistance information.

In another aspect, the present disclosure provides a BSS which isconfigured to interact with a SMLC. The BSS comprises a processor and amemory that stores processor-executable instructions, wherein theprocessor interfaces with the memory to execute the processor-executableinstructions, whereby the BSS is operable to perform a transmitoperation. In the transmit operation, the BSS transmits, to the SMLC, aBSSMAP-LE PERFORM LOCATION REQUEST message which includes an IE whichindicates a worst case synchronization accuracy of a mobile station. Anadvantage of the BSS performing this operation is that it enables a SMLCto make a better estimate of the accuracy of the estimated position ofthe mobile station as well as to make an a priori assessment as to howmany BTSs may be needed to reach the desired position accuracy and thusprovide the mobile station with more accurate assistance information.

In yet another aspect, the present disclosure provides a method in a BSSwhich is configured to interact with a SMLC. The method comprises atransmitting step. In the transmitting step, the BSS transmits, to theSMLC, a BSSMAP-LE PERFORM LOCATION REQUEST message which includes an IEwhich indicates a worst case synchronization accuracy of a mobilestation. An advantage of the BSS performing this step is that it enablesa SMLC to make a better estimate of the accuracy of the estimatedposition of the mobile station as well as to make an a priori assessmentas to how many BTSs may be needed to reach the desired position accuracyand thus provide the mobile station with more accurate assistanceinformation.

In one aspect, the present disclosure provides a BSS which includes aBTS and is configured to interact with a SMLC. The BSS comprises aprocessor and a memory that stores processor-executable instructions,wherein the processor interfaces with the memory to execute theprocessor-executable instructions, whereby the BSS is operable toperform a transmit operation. In the transmit operation, the BSStransmits, to the SMLC, a BSSMAP-LE CONNECTION ORIENTED INFORMATIONmessage which includes a BTS timing advance (TA) accuracy (271 ₁)estimated by the BTS. An advantage of the BSS performing this operationis that it enables a SMLC to make a better estimate of the accuracy ofthe estimated position of the mobile station.

In still yet another aspect, the present disclosure provides a method ina BSS which includes a BTS and is configured to interact with a SMLC.The method comprises a transmitting step. In the transmitting step, theBSS transmits, to the SMLC, a BSSMAP-LE CONNECTION ORIENTED INFORMATIONmessage which includes a BTS timing advance (TA) accuracy (271 ₁)estimated by the BTS. An advantage of the BSS performing this step isthat it enables a SMLC to make a better estimate of the accuracy of theestimated position of the mobile station.

Additional aspects of the present disclosure will be set forth, in part,in the detailed description, figures and any claims which follow, and inpart will be derived from the detailed description, or can be learned bypractice of the invention. It is to be understood that both theforegoing general description and the following detailed description areexemplary and explanatory only and are not restrictive of the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure may be obtainedby reference to the following detailed description when taken inconjunction with the accompanying drawings:

FIG. 1 (PRIOR ART) is a diagram of an exemplary wireless communicationnetwork used to help explain a problem associated with the traditionalmultilateration process in determining a position of a mobile station;

FIG. 2 is a diagram of an exemplary wireless communication network whichincludes a SGSN, multiple SMLCs, multiple BSSs, and a mobile stationwhich are configured in accordance with an embodiment of the presentdisclosure;

FIG. 3 is a diagram illustrating one possible coding of a MSsynchronization accuracy field which contains the mobile stationestimated assessment of the BTS timing (i.e., the mobile stationsynchronization accuracy) in accordance with an embodiment of thepresent disclosure;

FIG. 4 illustrates details of a BSSMAP-LE PERFORM LOCATION REQUESTmessage with a MS Symbol Granularity Capability IE (MS SynchronizationAccuracy IE) in accordance with an embodiment of the present disclosure;

FIG. 5 illustrates details of the MS Symbol Granularity Capability IE(MS Synchronization Accuracy IE) in accordance with an embodiment of thepresent disclosure;

FIGS. 6A-6B illustrate details of a MS Radio Access Capability IE whichincludes the MS Symbol Granularity Capability IE (MS SynchronizationAccuracy IE) in accordance with an embodiment of the present disclosure;

FIG. 7 is a diagram that illustrates a Multilateration TA (MTA) IE whichincludes an estimated BTS TA value and a BSS Granularity Capability inaccordance with an embodiment of the present disclosure;

FIG. 8 is a flowchart of a method implemented in the mobile station inaccordance with an embodiment of the present disclosure;

FIG. 9 is a block diagram illustrating a structure of the mobile stationconfigured in accordance with an embodiment of the present disclosure;

FIG. 10 is a flowchart of a method implemented in the BSS in accordancewith an embodiment of the present disclosure;

FIG. 11 is a block diagram illustrating a structure of the BSSconfigured in accordance with an embodiment of the present disclosure;

FIG. 12 is a flowchart of a method implemented in the BSS in accordancewith an embodiment of the present disclosure;

FIG. 13 is a block diagram illustrating a structure of the BSSconfigured in accordance with an embodiment of the present disclosure;

FIG. 14 is a flowchart of a method implemented in the BSS in accordancewith an embodiment of the present disclosure; and

FIG. 15 is a block diagram illustrating a structure of the BSSconfigured in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

A discussion is provided herein first to describe an exemplary wirelesscommunication network 200 that includes multiple BSSs 202 ₁, 202 ₂, 202₃, a mobile station 204, and multiple SMLCs 206 ₁ and 206 ₂ configuredto improve the accuracy in estimating a position of the mobile station204 in accordance with an embodiment of the present disclosure (see FIG.2). Then, a discussion is provided to disclose various techniques thatthe BSSs 202 ₁, 202 ₂, 202 ₃, and the mobile station 204 can use toenable the serving SMLC 206 ₁ to improve the accuracy in estimating aposition of the mobile station 204 in accordance with differentembodiments of the present disclosure (see FIGS. 3-7). Thereafter, adiscussion is provided to explain the basicfunctionalities-configurations of the mobile station 204 and the BSSs202 ₁, 202 ₂, 202 ₃, each of which are configured to improve theaccuracy in which the serving SMLC 206 ₁ can estimate a position of themobile station 204 in accordance with different embodiments of thepresent disclosure (see FIGS. 8-15).

Exemplary Wireless Communication Network 200

Referring to FIG. 2, there is illustrated an exemplary wirelesscommunication network 200 in accordance with the present disclosure. Thewireless communication network 200 includes a core network (CN) 208(which comprises at least one CN node 207 (e.g., SGSN 207)), multipleSMLCs 206 ₁ and 206 ₂, and multiple BSSs 202 ₁, 202 ₂, 202 ₃, (onlythree shown) which interface with a mobile station 204 (only one shown)(note: in practice there would be multiple mobile stations 204 but forclarity only one mobile station 204 is discussed herein). The wirelesscommunication network 200 also includes many well-known components, butfor clarity, only the components needed to describe the features of thepresent disclosure are described herein. Further, the wirelesscommunication network 200 is described herein as being a GSM/EGPRSwireless communication network 200 which is also known as an EDGEwireless communication network 200. However, those skilled in the artwill readily appreciate that the techniques of the present disclosurewhich are applied to the GSM/EGPRS wireless communication network 200are generally applicable to other types of wireless communicationsystems, including, for example, EC-GSM, WCDMA, LTE, and WiMAX systems.

The wireless communication network 200 includes the BSSs 202 ₁, 202 ₂,202 ₃ (which are basically wireless access nodes 202 ₁, 202 ₂, 202 ₃,RAN nodes 202 ₁, 202 ₂, 202 ₃, wireless access points 202 ₁, 202 ₂, 202₃) which can provide network access to the mobile station 204. Each BSS202 ₁, 202 ₂, 202 ₃ includes one or more BTSs 210 ₁, 210 ₂, 210 ₃ and aBSC 212 ₁, 212 ₂, 212 ₃. The BSSs 202 ₁, 202 ₂, 202 ₃ are connected tothe core network 208 and, in particular, to the CN node 207 (e.g., SGSN207). The core network 208 is connected to an external packet datanetwork (PDN) 219, such as the Internet, and a server 213 (only oneshown). The mobile station 204 may communicate with one or more servers213 (only one shown) connected to the core network 208 and/or the PDN219.

The mobile station 204 may be referred to generally as an end terminal(user) that attaches to the wireless communication network 200, and mayrefer to either a Machine Type Communications (MTC) device (e.g., asmart meter) or a non-MTC device. Further, the term “mobile station” isgenerally intended to be synonymous with the term mobile device,wireless device, “User Equipment,” or UE, as that term is used by 3GPP,and includes standalone mobile stations, such as terminals, cell phones,smart phones, tablets, Internet of Things (IoT) devices, cellular IoTdevices, and wireless-equipped personal digital assistants, as well aswireless cards or modules that are designed for attachment to orinsertion into another electronic device, such as a personal computer,electrical meter, etc . . . .

The mobile station 204 may include a transceiver circuit 214 forcommunicating with the BSSs 202 ₁, 202 ₂, 202 ₃ (RAN nodes 202 ₁, 202 ₂,202 ₃), and a processing circuit 216 for processing signals transmittedfrom and received by the transceiver circuit 214 and for controlling theoperation of the mobile station 204. The transceiver circuit 214 mayinclude a transmitter 218 and a receiver 220, which may operateaccording to any standard, e.g., the GSM/EDGE standard, and the EC-GSMstandard. The processing circuit 216 may include a processor 222 and amemory 224 for storing program code for controlling the operation of themobile station 204. The program code may include code for performing theprocedures as described hereinafter.

Each BTS 210 ₁, 210 ₂, 210 ₃ may include a transceiver circuit 226 ₁,226 ₂, 226 ₃ for communicating with the mobile station 204 (typicallymultiple mobile stations 204—only one shown for clarity) and theirrespective BSC 212 ₁, 212 ₂, 212 ₃, a processing circuit 228 ₁, 228 ₂,228 ₃ for processing signals transmitted from and received by thetransceiver circuit 226 ₁, 226 ₂, 226 ₃ and for controlling theoperation of the corresponding BTS 210 ₁, 210 ₂, 210 ₃. The transceivercircuit 226 ₁, 226 ₂, 226 ₃ may include a transmitter 230 ₁, 230 ₂, 230₃ and a receiver 232 ₁, 232 ₂, 232 ₃, which may operate according to anystandard, e.g., the GSM/EDGE standard, and the EC-GSM standard. Theprocessing circuit 228 ₁, 228 ₂, 228 ₃ may include a processor 234 ₁,234 ₂, 234 ₃, and a memory 236 ₁, 236 ₂, 236 ₃ for storing program codefor controlling the operation of the corresponding BTS 210 ₁, 210 ₂, 210₃. The program code may include code for performing the procedures asdescribed hereinafter.

Each BSC 212 ₁, 212 ₂, 212 ₃ may include a transceiver circuit 238 ₁,238 ₂, 238 ₃ for communicating with their respective BTS 210 ₁, 210 ₂,210 ₃ and SMLC 206 ₁, 206 ₂, a processing circuit 240 ₁, 240 ₂, 240 ₃for processing signals transmitted from and received by the transceivercircuit 238 ₁, 238 ₂, 238 ₃ and for controlling the operation of thecorresponding BSC 212 ₁, 212 ₂, 212 ₃, and a network interface 242 ₁,242 ₂, 242 ₃ for communicating with the SGSN 207 part of the corenetwork 208. The transceiver circuit 238 ₁, 238 ₂, 238 ₃ may include atransmitter 244 ₁, 244 ₂, 244 ₃ and a receiver 246 ₁, 246 ₂, 246 ₃,which may operate according to any standard, e.g., the GSM/EDGE standard(in this example), and the EC-GSM standard. The processing circuit 240₁, 240 ₂, 240 ₃ may include a processor 248 ₁, 248 ₂, 248 ₃, and amemory 250 ₁, 250 ₂, 250 ₃ for storing program code for controlling theoperation of the corresponding BSC 212 ₁, 212 ₂, 212 ₃. The program codemay include code for performing the procedures as described hereinafter.Note: for purposes of the discussion herein, it should be appreciatedthat the BSS 202 ₁, 202 ₂, 202 ₃ circuitry can be considered to be thesame circuitry as BSC 212 ₁, 212 ₂, 212 ₃ (it should be appreciated thata BSS comprises a BSC and a BTS according to well-known prior art, sowhen there is a discussion herein about a BSS performing certainfunctions, it typically means the BSC performing those functions unlessit is specifically mentioned that the BTS is performing a function).

The CN node 207 (e.g., SGSN 207, Mobility Management Entity (MME) 207)may include a transceiver circuit 252 for communicating with the BSSs202 ₁, 202 ₂, 202 ₃, a processing circuit 254 for processing signalstransmitted from and received by the transceiver circuit 252 and forcontrolling the operation of the CN node 207, and a network interface257 for communicating with the PDN 219 or the server 213. Thetransceiver circuit 252 may include a transmitter 256 and a receiver258, which may operate according to any standard, e.g., the GSM/EDGEstandard (in this example), and the EC-GSM standard. The processingcircuit 254 may include a processor 260 and a memory 262 for storingprogram code for controlling the operation of the CN node 207. Theprogram code may include code for performing the procedures as describedhereinafter.

Techniques for Improving Accuracy of Mobile Station's Estimated Position

Brief Description

In accordance with an embodiment of the present disclosure, the MS 204when synchronizing to a BTS 210 ₁, 210 ₂, 210 ₃ (three shown) alsoestimates the accuracy 264 ₁, 264 ₂, 264 ₃ by which it has synchronizedto the BTS 210 ₁, 210 ₂, 210 ₃. The MS 204 reports (e.g., in an uplinkRadio Link Control (RLC) data block 270 ₁, 270 ₂, 270 ₃) the estimatedsynchronization accuracy 264 ₁, 264 ₂, 264 ₃ associated with therespective BTS 210 ₁, 210 ₂, 210 ₃ to the network (e.g., BSS 202 ₁, 202₂, 202 ₃). The estimated synchronization accuracy 264 ₁, 264 ₂, 264 ₃ isforwarded by the network (e.g., BSS 202 ₁, 202 ₂, 202 ₃) to the servingSMLC 206 ₁ and taken into account by the serving SMLC 206 ₁ whenestimating the accuracy of the estimated position of the MS 204.Alternatively, in another embodiment of the present disclosure in orderto address scenarios where the MS 204 is not able to provide an estimateof the MS synchronization accuracy 264 ₁ to the serving SMLC 206 ₁,instead there is provided to the serving SMLC 206 ₁ an a prioriunderstanding of the MS capability, by having the serving BSS 202 ₁ usea field 266 (MS Symbol Granularity/MS Synchronization Accuracy 266 thatindicates the worst case synchronization accuracy of MS 204) which canbe added to a MS Radio Access Capability Information Element (IE) 267and sent to the serving SMLC 206 ₁ (see 3GPP TS 24.008 v14.1.0 whichdiscloses the traditional MS Radio Access Capability IE without the newMS Symbol Granularity/MS Synchronization Accuracy 266—the contents ofwhich are incorporated herein by reference). It is further proposed inyet another embodiment of the present disclosure that the serving BSS202 ₁ passes either the complete MS Radio Access Capability IE 267 orthe MS Symbol Granularity field 266 in a BSSMAP-LEPERFORM-LOCATION-REQUEST Protocol Data Unit (PDU) 269 to the servingSMLC 206 ₁ prior to the serving SMLC 206 ₁ triggering multilaterationfor the MS 204 (e.g., sending the MS 204 a multilateration request 272).

Moreover, in order for the serving SMLC 206 ₁ to be able to accuratelyassess the overall MS positioning accuracy, it could also utilize a BTSTA accuracy 271 ₁, 271 ₂, 271 ₃. To this end, it is therefore proposedin another embodiment of the present disclosure to add a means for theBSS 202 ₁, 202 ₂, 202 ₃ to indicate its BTS's TA estimation capability273 ₁, 273 ₂, 273 ₃ to the serving SMLC 206 ₁ in a BSSMAP-LE CONNECTIONORIENTED INFORMATION message 275 ₁, 275 ₂, 275 ₃ either as a new IE oras part of the BSSLAP APDU (note 1: BSS 202 ₁ transmits its BTS TAestimation capability directly to the serving SMLC 206 ₁ within aBSSMAP-LE CONNECTION ORIENTED INFORMATION message 275 ₁; the BSS 202 ₂first transmits its BTS TA estimation capability to the BSS 202 ₁ usinginter-BSS communication, then the BSS 202 ₁ transmits the BSSMAP-LECONNECTION ORIENTED INFORMATION message 275 ₂ to the serving SMLC 206 ₁(this signaling is not shown in FIG. 2); and the BSS 202 ₃ firsttransmits its BTS TA estimation capability to the BSS 202 ₁ using thecore network (e.g., SGSN 207), and the BSS 202 ₁ then transmits theBSSMAP-LE CONNECTION ORIENTED INFORMATION message 275 ₃ to the servingSMLC 206 ₁ (this signaling is not shown in FIG. 2)(note 2: FIG. 2 showsthe direct (logical) transmission of the BSSMAP-LE CONNECTION ORIENTEDINFORMATION MESSAGEs 275 ₂ and 275 ₃ from the BSSs 202 ₂ and 202 ₃ tothe serving SMLC 206 ₁). These embodiments of the present disclosurewill be discussed in more detail hereinafter.

DETAILED DESCRIPTION

As part of its synchronization process, the MS 204 estimates thesynchronization accuracy 264 ₁, 264 ₂, 264 ₃ by which it hassynchronized to the BTS 210 ₁, 210 ₂, 210 ₃ (note: the MS 204 willestimate a separate synchronization accuracy 264 ₁, 264 ₂, 264 ₃ foreach BTS 210 ₁, 210 ₂, 210 ₃). For example, the MS 204 can estimate thesynchronization accuracy 264 ₁, 264 ₂, 264 ₃ by performing multiplesynchronizations and measurements of the timing of the BTS 210 ₁, 210 ₂,210 ₃ and estimating the variance between these measurements. Forinstance, if N measurements of the timing are denoted t_(i), i=1, . . ., N, the variance of the individual measurement can be estimated usingthe well-known formula for unbiased sample variance:

$\begin{matrix}{s^{2} = {\frac{1}{N - 1}{\sum\limits_{i = 1}^{N}( {t_{i} - t} )^{2}}}} & ( {{equation}\mspace{14mu}{{no}.\mspace{14mu} 1}} )\end{matrix}$

where t is the mean of t_(i), i.e.,

$\begin{matrix}{\overset{\_}{t} = {\frac{1}{N}{\sum\limits_{i = 1}^{N}t_{i}}}} & ( {{equation}\mspace{14mu}{{no}.\mspace{14mu} 2}} )\end{matrix}$

Further, if the MS 204 finally estimates the timing of the BTS 210 ₁,210 ₂, 210 ₃ as the mean of the individual measurements (i.e., by t),the variance of this timing estimate can be estimated by:

$\begin{matrix}{{{var}( \overset{\_}{t} )} = \frac{s^{2}}{N}} & ( {{equation}\mspace{14mu}{{no}.\mspace{14mu} 3}} )\end{matrix}$

When synchronization is completed, the MS 204 will access the cell andreport the estimated synchronization accuracy 264 ₁, 264 ₂, 264 ₃ to thenetwork (e.g., the BSS 202 ₁, 202 ₂, 202 ₃).

Each BTS 210 ₁, 210 ₂, 210 ₃ will perform a TA estimation 271 ₁, 271 ₂,271 ₃ on its own based on the signal sent by the MS 204. As part of thisprocess, the BTS 210 ₁, 210 ₂, 210 ₃ will estimate the accuracy by whichit is able to measure the timing of signals received from the MS 204.From the accuracy (BTS timing advance accuracy 271 ₁, 271 ₂, 271 ₃)estimated by the BTS 210 ₁, 210 ₂, 210 ₃ and the accuracy estimated bythe MS 204, a total accuracy of the TA estimation can be derived. Thetotal accuracy is delivered together with the TA estimate 264 ₁, 264 ₂,264 ₃ and 271 ₁, 271 ₂, 271 ₃ to the serving SMLC 206 ₁. The servingSMLC 206 ₁ combines accuracy estimates of TA estimates 264 ₁, 264 ₂, 264₃ and 271 ₁, 271 ₂, 271 ₃ from multiple BTSs 210 ₁, 210 ₂, 210 ₃ toderive an estimate of the accuracy of the positioning of the MS 204.

In a first embodiment of the present disclosure, it is proposed to alsoinclude the estimated MS synchronization accuracy 264 ₁, in addition tothe Temporary Logical Link Identifier (TLLI) 274 (or other MS identity)of the MS 204, in the Radio Link Control (RLC) data block 270 ₁transmitted by the MS 204 on an uplink Temporary Block Flow (TBF)established in response to an access request 272 indicatingMultilateration. In order for the BSS 202 ₁ (e.g., serving BSS 202 ₁) toextract the MS estimated synchronization accuracy 264 ₁ from the uplinkRLC data block 270 ₁, it is proposed that the MS 204 use a reservedlength indicator 276, e.g., a length indicator 276 of value 122 in theRLC data block 270 ₁ (note that any of the unused length indicators maybe used). Length indicators are used to delimit upper layer PDU but mayalso be used to indicate the presence of additional information withinthe RLC data block. One example is the length indicator with a value125, which indicates the presence of dynamic timeslot reduction controlinformation which shall be included after the last Upper Layer PDU (see3GPP TS 44.060 V13.3.0 (2016-09)—the contents of which are incorporatedby reference herein). In the case of Multilateration, it is proposedthat a Length Indicator 276 of value 122 be used in the RLC data block270 ₁ by the MS 204 to indicate the presence of “MS synchronizationaccuracy” field 278 (which includes the estimated MS synchronizationaccuracy 264 ₁) in the first octet immediately following the LengthIndicator 276. FIG. 3 is a diagram illustrating one possible coding ofthe “MS synchronization accuracy” field 278 which contains the MSestimated assessment of the BTS 210 ₁ timing (i.e., the MS estimatedsynchronization accuracy 264 ₁) in units of 1/16 of a symbol period. Analternative coding may also be used.

In a second embodiment, it is proposed to also include the estimated MSsynchronization accuracy 264 ₂, 264 ₃, in addition to the TLLI 274 (orother MS identity) of the MS 204 and the Source Identity 280 of theServing BSS 202 ₁, in the RLC data blocks 270 ₂, 270 ₃ transmitted bythe MS 204 on an uplink TBF established in response to an access request272 indicating Multilateration. In order for the BSSs 202 ₂, 202 ₃(e.g., non-serving BSSs 202 ₂, 202 ₃) to extract the estimated MSsynchronization accuracy 264 ₂, 264 ₃ from the uplink RLC data blocks270 ₂, 270 ₃, it is proposed that the MS 204 uses a reserved lengthindicator 276, e.g., a length indicator 276 of value 122 within the RLCdata blocks 270 ₂, 270 ₃. In the case of Multilateration, it is proposedthat a Length Indicator 276 of value 122 is used in the RLC data blocks270 ₂, 270 ₃ by the MS 204 to indicate the presence of the “SourceIdentity” field 281 and MS synchronization accuracy field 278 in thefive octets immediately following the Length Indicator 276 (four octetsfor the Source Identity field 281 and one octet for the MSsynchronization accuracy field 278). The assumption of using four octetsfor the Source Identity field 281 can be seen as valid if it is alwayssufficient to provide two octets of Location Area Code (LAC) and twooctets of Cell ID information for the source identity (i.e., if it canbe assumed that only cells belonging to the same Public Land MobileNetwork (PLMN) are used for positioning). However, the “Source Identity”field 281 could alternatively comprise Mobile Country Code (MCC)+MobileNetwork Code (MNC)+LAC+Cell ID (i.e., a total of 7 octets) in order toaddress the case where knowledge of PLMN ID (MCC+MNC) is needed toforward the derived TA information 264 ₂, 264 ₃ and associated Cell IDinformation 280 from a non-serving BSS 202 ₂ and 202 ₃ to the servingBSS 202 ₁. For a possible coding of the MS synchronization accuracyfield 278, see FIG. 3.

In a third embodiment, in order to address a scenario when there is noassessment of the MS synchronization accuracy 264 ₁ from the MS 204, itis proposed to add means for the serving BSS 202 ₁ to pass the MS SymbolGranularity Capability IE 266 (MS Synchronization Accuracy IE 266 whichindicates the worst case synchronization accuracy of MS 204) to theserving SMLC 206 ₁ in the BSSMAP-LE PERFORM LOCATION REQUEST message 269sent from the serving BSS 202 ₁ to the serving SMLC 206 ₁. FIG. 4illustrates details of the BSSMAP-LE PERFORM LOCATION REQUEST message269 with the new MS Symbol Granularity Capability IE 266 (MSSynchronization Accuracy IE 266) (note: the reference to TABLE 9.1 3GPPTS 49.031 indicates that this table will be updated in the new standardto reflect the updated BSSMAP-LE PERFORM LOCATION REQUEST message 269per the present disclosure). FIG. 5 illustrates details of the new MSSymbol Granularity Capability IE 266 (MS Synchronization Accuracy IE266) which is a variable length information element that indicates theMultilateration symbol granularity of the target MS 204 (note: thereference to 10.34 3GPP TS 49.031 indicates that this figure will beupdated in the new standard to reflect the new MS Symbol GranularityCapability IE 266 (MS Synchronization Accuracy IE 266) per the presentdisclosure). Alternatively, the serving BSS 202 ₁ using a field 266 (MSSymbol Granularity 266/MS Synchronization Accuracy 266) that indicatesthe worst case synchronization accuracy of MS 204 is added to the MSRadio Access Capability IE 267 which can be forwarded from the BSS 202 ₁to the SMLC 206 ₁ as received by the BSS 202 ₁ from the SGSN 207. FIGS.6A-6B illustrate details of the MS Radio Access Capability IE 267 withthe new MS Symbol Granularity Capability IE 266 (MS SynchronizationAccuracy IE 266) (note: the reference to TABLE 10.5.146 3GPP TS 24.008indicates that this table will be updated in the new standard to reflectthe MS Symbol Granularity Capability IE 266 per the present disclosure).In yet another alternative, the complete MS Radio Access Capability IE267 is sent as a new IE in the BSSMAP-LE PERFORM LOCATION REQUESTmessage 269 or the MS Symbol Granularity Capability IE 266 is added tothe Classmark Information Type 3 message already optionally included inthe BSSMAP-LE PERFORM LOCATION REQUEST message 269.

In a fourth embodiment, in order for the serving SMLC 206 ₁ to know theaccuracy of the BSS 202 ₁, 202 ₂, 202 ₃ (BTS 210 ₁, 210 ₂, 210 ₃)estimation of the TA 271 ₁, 271 ₂, 271 ₃, it is proposed to add meansfor the BSS 202 ₁, 202 ₂, 202 ₃ (BTS 210 ₁, 210 ₂, 210 ₃) to indicateits TA estimation capability 273 ₁, 273 ₂, 273 ₃ to the serving SMLC 206₁ in the BSSMAP-LE CONNECTION ORIENTED INFORMATION message 275 ₁, 275 ₂,275 ₃, either as a new IE or as part of the BSSLAP APDU. FIG. 7 is adiagram that illustrates where a new 3GPP TS 49.031 Multilateration TA(MTA) IE 277 is proposed to not only carry the estimated TA value 271 ₁,271 ₂, 271 ₃ but also the BSS Granularity Capability (bits 2 to 4 ofoctet 2) 273 ₁, 273 ₂, 273 ₃, which indicates the symbol granularityused by the BSS 202 ₁, 202 ₂, 202 ₃ (BTS 210 ₁, 210 ₂, 210 ₃) whenestimating TA 271 ₁, 271 ₂, 271 ₃ (note: the “MTA High” and “MTA Low”fields carry the estimated TA value 271 ₁, 271 ₂, 271 ₃) during theMultilateration procedure. Alternatively, the same information couldalso have been included in the BSSLAP APDU as a new 3GPP 48.071Multilateration Timing Advance (MTA) message.

Basic Functionalities-Configurations of the MS 204 and the BSS 202 ₁,202 ₂, 202 ₃

Referring to FIG. 8, there is a flowchart of a method 800 implemented inthe mobile station 204 that is configured to interact with BSS 202 ₁(the serving BSS 202 ₁) which includes BTS 210 ₁ (for example) inaccordance with an embodiment of the present disclosure. At step 802,the mobile station 204 receives, from the BSS 202 ₁, a multilaterationrequest 272 (note: the serving SMLC 206 ₁ originally transmits themultilateration request 272 which is then transmitted by the BSS 202 ₁to the mobile station 204). At step 804, the mobile station 204estimates a synchronization accuracy 264 ₁ with the BTS 210 ₁ inresponse to receiving the multilateration request 272. For instance, themobile station 204 can estimate the synchronization accuracy 264 ₁ withthe BTS 210 ₁ by performing multiple timing measurements of the BTS 210₁ and estimating a variance between the timing measurements of the BTS210 ₁ (note: the variance can be estimated as discussed above withrespect to equation nos. 1-3). At step 806, the mobile station 204transmits, to the BSS 202 ₁, a RLC data block 270 ₁ that includes atleast (i) a TLLI 274 of the mobile station 204, and (ii) the estimatedsynchronization accuracy 264 ₁. The RLC data block 270 ₁ may furtherinclude (iii) a Source Identity 280 of the BSS 202 ₁, and (iv) a lengthindicator 276 to indicate a presence of the estimated synchronizationaccuracy 264 ₁. It should be appreciated that the mobile station 204would also perform at least steps 804 and 806 with the non-serving BSSs202 ₂ and 202 ₃.

Referring to FIG. 9, there is a block diagram illustrating structures ofan exemplary mobile station 204 in accordance with an embodiment of thepresent disclosure. In one embodiment, the mobile station 204 comprisesa receive module 902, an estimate module 904, and a transmit module 906.The receive module 902 is configured to receive from a BSS 202 ₁ (forexample) a multilateration request 272. The estimate module 904 isconfigured to estimate a synchronization accuracy 264 ₁ with a BTS 210 ₁of the BSS 202 ₁ in response to receipt of the multilateration request272. The transmit module 906 is configured to transmit to the BSS 202 ₁,a RLC data block 270 ₁ that includes at least (i) a TLLI 274 of themobile station 204, and (ii) the estimated synchronization accuracy 264₁. The RLC data block 270 ₁ may further include (iii) a Source Identity280 of the BSS 202 ₁, and (iv) a length indicator 276 to indicate apresence of the estimated synchronization accuracy 264 ₁. It should benoted that the mobile station 204 may also include other components,modules or structures which are well-known, but for clarity, only thecomponents, modules or structures needed to describe the features of thepresent disclosure are described herein.

As those skilled in the art will appreciate, the above-described modules902, 904, and 906 of the mobile station 204 may be implementedseparately as suitable dedicated circuits. Further, the modules 902,904, and 906 can also be implemented using any number of dedicatedcircuits through functional combination or separation. In someembodiments, the modules 902, 904, and 906 may be even combined in asingle application specific integrated circuit (ASIC). As an alternativesoftware-based implementation, the mobile station 204 may comprise amemory 224, a processor 222 (including but not limited to amicroprocessor, a microcontroller or a Digital Signal Processor (DSP),etc.) and a transceiver 214. The memory 224 stores machine-readableprogram code executable by the processor 222 to cause the mobile station204 to perform the steps of the above-described method 800.

Referring to FIG. 10, there is a flowchart of a method 1000 implementedin the BSS 202 ₁ (for example) which includes BTS 210 ₁ (for example)and is configured to interact with mobile station 204 in accordance withan embodiment of the present disclosure. At step 1002, the BSS 202 ₁transmits, to the mobile station 204, a multilateration request 272(note: the serving SMLC 206 ₁ originally transmits the multilaterationrequest 272 which is then transmitted by the BSS 202 ₁ to the mobilestation 204). At step 1004, the BSS 202 ₁ receives, from the mobilestation 204, a RLC data block 270 ₁ that includes at least (i) a TLLI274 of the mobile station 204, and (ii) an estimated mobile stationsynchronization accuracy 264 ₁, wherein the estimated synchronizationaccuracy 264 ₁ indicates an estimate by the mobile station 204 of anaccuracy by which the mobile station 204 is synchronized to the BTS 210₁. The RLC data block 270 ₁ may further include (iii) a Source Identity280 of the BSS 202 ₁, and (iv) a length indicator 276 to indicate apresence of the estimated synchronization accuracy 264 ₁. It should beappreciated that the BSSs 202 ₂ and 202 ₃ would also perform at leaststep 1004 with the mobile station 204.

Referring to FIG. 11, there is a block diagram illustrating structuresof an exemplary BSS 202 ₁ (for example) in accordance with an embodimentof the present disclosure. In one embodiment, the BSS 202 ₁ comprises atransmit module 1102 and a receive module 1104.

The transmit module 1102 is configured to transmit, to the mobilestation 204, a multilateration request 272. The receive module 1104 isconfigured to receive, from the mobile station 204, a RLC data block 270₁ that includes at least (i) a TLLI 274 of the mobile station 204, and(ii) an estimated mobile station synchronization accuracy 264 ₁, whereinthe estimated synchronization accuracy 264 ₁ indicates an estimate bythe mobile station 204 of an accuracy by which the mobile station 204 issynchronized to the BTS 210 ₁. The RLC data block 270 ₁ may furtherinclude (iii) a Source Identity 280 of the BSS 202 ₁, and (iv) a lengthindicator 276 to indicate a presence of the estimated synchronizationaccuracy 264 ₁. It should be noted that the BSS 202 ₁ may also includeother components, modules or structures which are well-known, but forclarity, only the components, modules or structures needed to describethe features of the present disclosure are described herein.

As those skilled in the art will appreciate, the above-described modules1102 and 1104 of the BSS 202 ₁ may be implemented separately as suitablededicated circuits. Further, the modules 1102 and 1104 can also beimplemented using any number of dedicated circuits through functionalcombination or separation. In some embodiments, the modules 1102 and1104 may be even combined in a single application specific integratedcircuit (ASIC). As an alternative software-based implementation, the BSS202 ₁ may comprise a memory 250 ₁, a processor 248 ₁ (including but notlimited to a microprocessor, a microcontroller or a Digital SignalProcessor (DSP), etc.) and a transceiver 238 ₁. The memory 250 ₁ storesmachine-readable program code executable by the processor 248 ₁ to causethe BSS 202 ₁ to perform the steps of the above-described method 1000.Note 1: the BSS 202 ₁ in addition to performing method 1000 may alsoperform methods 1200 and/or 1400. Note 2: the other BSSs 202 ₂ and 202 ₃may be configured the same as BSS 202 ₁.

Referring to FIG. 12, there is a flowchart of a method 1200 implementedin the BSS 202 ₁ (for example) which is configured to interact with theSMLC 206 ₁ in accordance with an embodiment of the present disclosure.At step 1202, the BSS 202 ₁ transmits, to the SMLC 206 ₁, a BSSMAP-LEPERFORM LOCATION REQUEST message 269 which includes an InformationElement (IE) 266 (MS Symbol Granularity IE 266, MS SynchronizationAccuracy IE 266) which indicates a worst case synchronization accuracyof a mobile station 204 (see FIGS. 4-5). In one example, the IE 266 (MSSymbol Granularity IE 266, MS Synchronization Accuracy IE 266) whichindicates the worst case synchronization accuracy of the mobile station204 is part of a MS Radio Access Capability Information Element 267 (seeFIGS. 6A-6B). It should be appreciated that the BSSs 202 ₂ and 202 ₃ mayalso perform method 1200.

Referring to FIG. 13, there is a block diagram illustrating structuresof an exemplary BSS 202 ₁ (for example) in accordance with an embodimentof the present disclosure. In one embodiment, the BSS 202 ₁ comprises atransmit module 1302. The transmit module 1302 is configured totransmit, to the SMLC 206 ₁, a BSSMAP-LE PERFORM LOCATION REQUESTmessage 269 which includes an Information Element (IE) 266 (MS SymbolGranularity IE 266, MS Synchronization Accuracy IE 266) which indicatesa worst case synchronization accuracy of a mobile station 204 (see FIGS.4-5). In one example, the IE 266 (MS Symbol Granularity IE 266, MSSynchronization Accuracy IE 266) which indicates the worst casesynchronization accuracy of the mobile station 204 is part of a MS RadioAccess Capability Information Element 267 (see FIGS. 6A-6B). It shouldbe noted that the BSS 202 ₁ may also include other components, modulesor structures which are well-known, but for clarity, only thecomponents, modules or structures needed to describe the features of thepresent disclosure are described herein.

As those skilled in the art will appreciate, the above-described module1302 of the BSS 202 ₁ may be implemented in a suitable dedicatedcircuit. Further, the module 1302 can also be implemented using anynumber of dedicated circuits through functional combination orseparation. In some embodiments, the module 1302 may be even combined ina single application specific integrated circuit (ASIC). As analternative software-based implementation, the BSS 202 ₁ may comprise amemory 250 ₁, a processor 248 ₁ (including but not limited to amicroprocessor, a microcontroller or a Digital Signal Processor (DSP),etc.) and a transceiver 238 ₁. The memory 250 ₁ stores machine-readableprogram code executable by the processor 248 ₁ to cause the BSS 202 ₁ toperform the steps of the above-described method 1200. Note 1: the BSS202 ₁ in addition to performing method 1200 may also perform methods1000 and/or 1400. Note 2: the other BSSs 202 ₂ and 202 ₃ may beconfigured the same as BSS 202 ₁.

Referring to FIG. 14, there is a flowchart of a method 1400 implementedin the BSS 202 ₁ (for example) which includes a BTS 210 ₁ (for example)and which is configured to interact with the SMLC 206 ₁ in accordancewith an embodiment of the present disclosure. At step 1202, the BSS 202₁ transmits, to the SMLC 206 ₁, a BSSMAP-LE CONNECTION ORIENTEDINFORMATION message 275 ₁ which includes a BTS TA accuracy 271 ₁estimated by the BTS 210 ₁. In one example, the estimated BTS TAaccuracy 271 ₁ can be part of a BSSLAP APDU. It should be appreciatedthat the BSSs 202 ₂ and 202 ₃ may also perform method 1400.

Referring to FIG. 15, there is a block diagram illustrating structuresof an exemplary BSS 202 ₁ (for example) in accordance with an embodimentof the present disclosure. In one embodiment, the BSS 202 ₁ comprises atransmit module 1502. The transmit module 1502 is configured totransmit, to the SMLC 206 ₁, a BSSMAP-LE CONNECTION ORIENTED INFORMATIONmessage 275 ₁ which includes a BTS TA accuracy 271 ₁ estimated by theBTS 210 ₁. In one example, the estimated BTS TA accuracy 271 ₁ can bepart of a BSSLAP APDU. It should be noted that the BSS 202 ₁ may alsoinclude other components, modules or structures which are well-known,but for clarity, only the components, modules or structures needed todescribe the features of the present disclosure are described herein.

As those skilled in the art will appreciate, the above-described module1502 of the BSS 202 ₁ may be implemented in a suitable dedicatedcircuit. Further, the module 1502 can also be implemented using anynumber of dedicated circuits through functional combination orseparation. In some embodiments, the module 1502 may be even combined ina single application specific integrated circuit (ASIC). As analternative software-based implementation, the BSS 202 ₁ may comprise amemory 250 ₁, a processor 248 ₁ (including but not limited to amicroprocessor, a microcontroller or a Digital Signal Processor (DSP),etc.) and a transceiver 238 ₁. The memory 250 ₁ stores machine-readableprogram code executable by the processor 248 ₁ to cause the BSS 202 ₁ toperform the steps of the above-described method 1400. Note 1: the BSS202 ₁ in addition to performing method 1400 may also perform methods1000 and/or 1200. Note 2: the other BSSs 202 ₂ and 202 ₃ may beconfigured the same as BSS 202 ₁.

Those skilled in the art will appreciate that the use of the term“exemplary” is used herein to mean “illustrative,” or “serving as anexample,” and is not intended to imply that a particular embodiment ispreferred over another or that a particular feature is essential.Likewise, the terms “first” and “second,” and similar terms, are usedsimply to distinguish one particular instance of an item or feature fromanother, and do not indicate a particular order or arrangement, unlessthe context clearly indicates otherwise. Further, the term “step,” asused herein, is meant to be synonymous with “operation” or “action.” Anydescription herein of a sequence of steps does not imply that theseoperations must be carried out in a particular order, or even that theseoperations are carried out in any order at all, unless the context orthe details of the described operation clearly indicates otherwise.

Of course, the present disclosure may be carried out in other specificways than those herein set forth without departing from the scope andessential characteristics of the invention. One or more of the specificprocesses discussed above may be carried out in a cellular phone orother communications transceiver comprising one or more appropriatelyconfigured processing circuits, which may in some embodiments beembodied in one or more application-specific integrated circuits(ASICs). In some embodiments, these processing circuits may comprise oneor more microprocessors, microcontrollers, and/or digital signalprocessors programmed with appropriate software and/or firmware to carryout one or more of the operations described above, or variants thereof.In some embodiments, these processing circuits may comprise customizedhardware to carry out one or more of the functions described above. Thepresent embodiments are, therefore, to be considered in all respects asillustrative and not restrictive.

Although multiple embodiments of the present disclosure have beenillustrated in the accompanying Drawings and described in the foregoingDetailed Description, it should be understood that the invention is notlimited to the disclosed embodiments, but instead is also capable ofnumerous rearrangements, modifications and substitutions withoutdeparting from the present disclosure that as has been set forth anddefined within the following claims.

The invention claimed is:
 1. A base station subsystem (BSS) configuredto interact with a Serving Mobile Location Center (SMLC), the BSScomprising: a processor; and, a memory that stores processor-executableinstructions, wherein the processor interfaces with the memory toexecute the processor-executable instructions, whereby the BSS isoperable to: transmit, to the SMLC, a Base Station Subsystem MobileApplication Part-Location Services Extension (BSSMAP-LE) PERFORMLOCATION REQUEST message which includes an Information Element (IE)which indicates a worst case synchronization accuracy of a mobilestation.
 2. The BSS of claim 1, wherein the IE which indicates the worstcase synchronization accuracy of the mobile station is part of a MobileStation (MS) Radio Access Capability Information Element.
 3. A method ina base station subsystem (BSS) configured to interact with a ServingMobile Location Center (SMLC), the method comprising: transmitting, tothe SMLC, a Base Station Subsystem Mobile Application Part-LocationServices Extension (BSSMAP-LE) PERFORM LOCATION REQUEST message whichincludes an Information Element (IE) which indicates a worst casesynchronization accuracy of a mobile station.
 4. The method of claim 3,wherein the IE which indicates the worst case synchronization accuracyof the mobile station is part of a Mobile Station (MS) Radio AccessCapability Information Element.
 5. A base station subsystem (BSS)configured to interact with a Serving Mobile Location Center (SMLC) andincluding a base transceiver station (BTS), the BSS comprising: aprocessor; and, a memory that stores processor-executable instructions,wherein the processor interfaces with the memory to execute theprocessor-executable instructions, whereby the BSS is operable to:transmit, to the SMLC, a Base Station Subsystem Mobile ApplicationPart-Location Services Extension (BSSMAP-LE) CONNECTION ORIENTEDINFORMATION message which includes a BTS timing advance (TA) accuracyestimated by the BTS.
 6. The BSS of claim 5, wherein the estimated BTSTA accuracy is part of a Base Station Subsystem Location ServicesAssistance Protocol (BSSLAP) Application Protocol Data Unit (APDU).
 7. Amethod in a base station subsystem (BSS) which includes a basetransceiver station (BTS) and is configured to interact with a ServingMobile Location Center (SMLC), the method comprising: transmitting, tothe SMLC, a Base Station Subsystem Mobile Application Part-LocationServices Extension (BSSMAP-LE) CONNECTION ORIENTED INFORMATION messagewhich includes a BTS timing advance (TA) accuracy estimated by the BTS.8. The method of claim 7, wherein the estimated BTS TA accuracy is partof a Base Station Subsystem Location Services Assistance Protocol(BSSLAP) Application Protocol Data Unit (APDU).
 9. The BSS of claim 1,wherein the worst case synchronization accuracy of the mobile station isan a priori understanding of a capability of the mobile station.
 10. TheBSS of claim 1, wherein the IE indicates the worst case synchronizationaccuracy of the mobile station by utilizing a multi-bit field whichindicates that the mobile station has a capability to support one of aplurality of pre-defined multilateration symbol granularities.
 11. Themethod of claim 3, wherein the worst case synchronization accuracy ofthe mobile station is an a priori understanding of a capability of themobile station.
 12. The method of claim 3, wherein the IE indicates theworst case synchronization accuracy of the mobile station by utilizing amulti-bit field which indicates that the mobile station has a capabilityto support one of a plurality of pre-defined multilateration symbolgranularities.